Though not illustrated, a conventional substrate storage container includes a container body for accommodating semiconductor wafers, a door that is detachably attached to open and close the open front of this container body, and a locking mechanism for locking the door fitted to the front of the container body, the locking mechanism being provided in the door (see Patent Documents 1, 2, 3 and 4).
For example, the container body is formed of a predetermined molding material and given in the form of a front-open box for accommodating a plurality of semiconductor wafers in vertical alignment while locking holes for a locking mechanism are formed at right and left positions on both the upper and the lower inner peripheral part in the front. On the other hand, the door is formed with such dimensions that the thickness is specified in conformity with the global standards, i.e., the SEMI Standards while retraction holes for the locking mechanism are formed at the positions opposing the corresponding locking holes of the container body. The door is fitted to, or removed from, the open front of the container body by means of door opening and closing equipment which holds the door by vacuum suctioning.
There are various types of locking mechanisms. A type disclosed in Patent Document 1 is formed of, for example, a plurality of cam plates that are operated to rotate from the outside of the door by means of door opening and closing equipment, and a plurality of latch bars that slide into, and out of, locking holes of the container body as each cam plate rotates. These plural cam plates and latch bars are separately formed of predetermined molding materials, and the latch bar is connected to either the front or rear face of the cam plate while inclined projections for the latch bar are projectively formed on the front side of the cam plate.
The locking mechanism of a type disclosed in Patent Document 2 is formed of a plurality of cam plates that are operated to rotate from the outside of the door, and a plurality of latch bars that are coupled with each cam plate via a cam follower at the end thereof and move into and separate from locking holes of the container body. These plural cam plates and latch bars are separately formed of predetermined materials. An inclined projection as a three-dimensional cam for the latch bar is projectively formed on the front side of the cam plate while the cam follower of the latch bar is formed in an approximately S-curved shape.
The locking mechanism of a type disclosed in Patent Document 3 basically has the same configuration as the above types, being formed of molded multiple cam plates in combination with latch bars. However, a protruded lip for the latch bar is formed at the peripheral part of the cam plate while the end of the latch bar is not formed linearly but is formed into two branches.
The locking mechanism of a type disclosed in Patent Document 4 is formed of a plurality of rotary plates that are operated to rotate from the outside of the door by means of door opening and closing equipment, a plurality of vertically and retractable connection bars with their connection pins inserted in circular arc slots that are cut out through the peripheral part of each rotary plate, and a plurality of locking claws that sway to come out from the retraction holes of the door and enter the locking holes of the container body as each connection bar moves outwards. The plural rotary plates, connection bars and locking claws are separately formed of predetermined molding materials. The locking claw is pivotably supported by means of multiple durable metallic pins in the interior part of the retraction hole and the front end of the connection bar.
With the thus configured substrate storing container, the door is fitted shallowly to the open front of the container body by means of door opening and closing equipment so that the front side of the door is more or less projected outside the front face of the container body (the door is made to stop at a position 3 mm to the front side from the locking holes of the container body, or in a state of it being not completely fitted), then the locking mechanism is operated by means of door opening and closing equipment so that the distal ends or locking claws of the latch bars are engaged into the locking holes of the container body while the door that has been shallowly fitted inside the front of the container body is drawn deeply therein, whereby the door is correctly fitted to the front of the container body and firmly locked.
In locking this door, the distal end of the latch bar or the locking claw comes in slight contact with the wall surface on the front side that defines the locking hole, in the stage where the front side of the door is more or less projected outward relative to the front of the container body. Then, as the latch end or the locking claw is slid and obliquely and deeply inserted into the locking hole and engaged, whereby the door is sufficiently pulled in until the front face of the door is flush with the front face of the container body.